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Detection of serinecarbapenemase and Metallocarbapenemase enzymes in Klebsiella pneumoniae in a tertiary care hospital
B. Radhika and I. Jyothi Padmaja
GEMS Medical College, Ragolu, Srikakulam, Andhra Pradesh, India
Various carbapenems have been reported in K.pneumoniae such as KPC,VIM,NDM & OXA-48 etc. In addition, carbapenemase producers are usually associated with many other non - ß-lactam resistance determinants which give rise to multidrug and pan drug resistant isolates. Detection of these enzymes in infected patients and in carriers are the two main approaches for prevention of their spread. Potential carbapenamase producers are currently screened 1st by susceptibility testing, using breakpoint values for carbapenems. However many carbapenemase producers donot confer obvious resistance levels to carbapenems. So there is need for laboratories to search for carbapenemase producers. In such instance, phenotypic based test such as Modified Hodge Test (MHT) is very much useful in confirming invitro producton of carbapenemase enzymes. But this test doesnot differentiate serine carbapenemase enzyme (i.e Ambler class A & C) from metallocarbapenemase(i.e Ambler class B). To differentiate these two enzymes MHT positive isolates can be subjected to Disc Synergy test. These two tests are highly sensitive and specific and adaptable to any laboratory in the world. Out of 100 ceftazidime resistant K.pneumoniae 75 (75%) were sensitive, 7 (7%) were intermediate sensitive and 18 (18%) were resistant to imipenem. When the 18 imipenem resistant strains were subjected to Modified Hodge test, 15 gave positive results. When the 15 MHT positive strains subjected to disc synergy test 8 were positive and 7 were negative showing that 8 were producing metallocarbapenemases and 7 were producing serinecarbapenemases. Out of 7 intermediately imipenem sensitive isolates 2 were producing metallocarbapenemase and 3 were producing serine carbapenemase. Hence total number of imipenem resistant K.pneumoniae isolates were 23.
Keywords: Imipenem, Serine carbapenemase, Metallocarbapenemase,Modified Hodge test, Disc Synergy test.
Published online 3 August, 2015
© 2015 Published by Global Science Publishing Group, USA
Cite this Article as
B. Radhika and I. Jyothi Padmaja (2015). Detection of serinecarbapenemase and Metallocarbapenemase enzymes in Klebsiella pneumoniae in a tertiary care hospital. The Ame J Sci & Med Res, 1(1):136-147. doi:10.17812/ajsmr20151123.
The Ame J Scie & Med Res, Volume 1, Issue 1